TW201411659A - Conductive film forming method and sintering promoter - Google Patents

Abstract

In a conductive film forming method using photo sintering, a conductive film having low electric resistance is easily formed. Disclosed is a conductive film forming method in which a conductive film is formed using a photo sintering, which includes the steps of: forming a liquid film 2 made of a copper particulate dispersion on a substrate 1, drying the liquid film 2 to form a copper particulate layer 3, subjecting the copper particulate layer 3 to photo sintering to form a conductive film 4, attaching a sintering promoter 5 to the conductive film 4, and further subjecting the conductive film 4 having the sintering promoter 5 attached to photo sintering. The sintering promoter 5 is a compound which removes copper oxide from metallic copper. Thereby, the sintering promoter 5 removes a surface oxide film of copper particulates 21 in the conductive film 4.

Description

Conductive film forming method and sintering accelerator

The present invention relates to a method of forming a conductive film using photo sintering, and a sintering accelerator which allows photo sintering to be performed in a method of forming a conductive film.

There has been a printed circuit board in which a circuit composed of a copper foil is formed on a substrate by photolithography. Photolithography requires a step of etching a copper foil, and requires high cost to process the waste liquid generated by the etching.

A method is known as a technique which does not require etching, in which a conductive film is formed on a substrate by using a copper particulate dispersant (copper ink) containing copper particles (copper nanoparticles) dispersed in a dispersion medium (see, for example, Patent Document 1) ). According to this method, a liquid film of a copper particulate dispersant is formed on a substrate, and the liquid film is dried to form a copper particulate layer. The copper particulate layer is photo-sintered by light irradiation, and thereby a conductive film having low electrical resistance is formed.

However, in the above method, even if the light energy irradiated in the photo sintering is increased, the photo sintering may not be sufficiently performed, and thus the conductive film having a low electric resistance cannot be formed.

[Previous Technical Literature]

Patent Document 1: U.S. Patent Application No. 2008/0286488.

The present invention has been made to solve the above problems, and an object thereof is to easily form a conductive film having low electrical resistance by photo sintering in a method of forming a conductive film.

The method for forming a conductive film of the present invention is a method for forming a conductive film by photo sintering, and is characterized by comprising the steps of: forming a liquid film made of a copper particulate dispersant on a substrate, drying the liquid film to form a copper fine particle layer, photo-sintering the copper fine particle layer to form a conductive film, attaching a sintering accelerator to the conductive film, and further photo-sintering the conductive film having the adhered sintering accelerator, the sintering accelerator is moved from the metal copper A compound other than copper oxide.

In the method for forming a conductive film, the sintering accelerator is preferably selected from the group consisting of guanamines, sulfonamides, ketones, urethanes, thioethers, carboxylic acids, and phosphoric acids. group.

In the method of forming a conductive film, the sintering accelerator is preferably selected from the group consisting of polylysine, polyvinylpyrrolidone, dimethylacetamide, dimethylformamide, and polyamidamine film. a group consisting of polyamido lacquer, polyamidoximine, acetamidine, gamma-butyrolactone, acetic acid, a low molecular weight unsaturated polycarboxylic acid polymer, and a phosphate ester.

In the method of forming a conductive film, the sintering accelerator may be selected from the group consisting of alcohols, saccharides, aldehydes, hydrazines, quinones, phenols, and amines.

In the method for forming a conductive film, the sintering accelerator is preferably selected from the group consisting of methanol, isopropanol, ethylene glycol, 3-methoxy-3-methylbutanol, and diethylene glycol mono-2- Diethylene glycol mono-2-ethylhexyl ether, polyethylene glycol, L-sorbitol, Kent paper, furfural, hydrazine, hydroquinone, hydroxybutylanisole (hydroxybutyl anisole), a group consisting of hydroxylamine, triethanolamine, and morpholine.

In the conductive film forming method, preferably, in the step of attaching the sintering accelerator to the conductive film, a sintering accelerator is coated on the conductive film.

In the method of forming a conductive film, in the step of adhering the sintering accelerator to the conductive film, the sintering accelerator can be attached to the conductive film by irradiation with light.

The sintering accelerator of the present invention is used in the above-described method for forming a conductive film.

According to the present invention, since the sintering accelerator removes the surface oxide film of the copper particles in the conductive film in the photo sintering after the sintering accelerator is attached to the conductive film, the copper having the surface oxide film removed is further removed. The particles are sintered, and thus a conductive film having a low electrical resistance is easily formed.

1‧‧‧Substrate

2‧‧‧Liquid film

3‧‧‧ copper particle layer

4‧‧‧Electrical film

5‧‧‧Sintering accelerator

6‧‧‧Electrical film

21‧‧‧ copper particles

1(a) to 1(f) are schematic cross-sectional views showing the formation of a conductive film by a method of forming a conductive film according to an embodiment of the present invention in chronological order.

A method of forming a conductive film according to an embodiment of the present invention will be described with reference to FIGS. 1(a) to 1(f). As shown in Figs. 1(a) and 1(b), a liquid film 2 made of a copper particulate dispersant is formed on the substrate 1.

The substrate 1 is obtained by forming a substrate into a plate shape. Examples of substrates include, but are not limited to, glass, resins, ceramics, tantalum wafers, and the like.

The copper particulate dispersant is a liquid containing copper particles 21 dispersed therein, and the copper particulate dispersant includes copper particles 21, a dispersion medium, and a dispersant. The copper particles 21 are, for example, copper nanoparticles having a particle diameter of 1 nm or more and less than 100 nm. The dispersion medium is a liquid medium comprising copper particles 21. The dispersant allows the copper particles 21 to be dispersed in the dispersion medium. Since the surface of the fine particles is oxidized by oxygen in the air, the copper fine particles 21 are covered with a thin surface oxide film.

The liquid film 2 is formed, for example, by a printing method. In the printing method, a copper particulate dispersant is used as the printing ink, and a predetermined pattern is printed on the substrate 1 by a printing device, thereby forming a patterned liquid film 2.

Next, the liquid film 2 is dried. As shown in FIG. 1(c), copper particles 21 are deposited on the substrate 1 by drying the liquid film 2 to form a copper particle layer 3 composed of copper particles 21 on the substrate 1.

Next, the copper particle layer 3 is irradiated with light, and the copper particle layer 3 is photo sintered. As shown in FIG. 1(d), the conductive film 4 is formed by photo sintering the copper fine particle layer 3. Photo sintering is performed at room temperature in the atmosphere. The light source used in photo sintering is, for example, a xenon lamp. The laser device can also be used as a light source. This photo sintering is performed to such an extent that the copper particles 21 are not dissolved in the liquid even if the liquid is coated on the electroconductive film 4. Thus, for example, light-based sintered performed under the following conditions: irradiation energy of the light is in the range from 0.5J / cm ² to 30J / cm ^2, the irradiation time is in the range of 0.1ms to 10ms, and the number of irradiation time . In this photo sintering, the conductive film 4 is not sufficiently agglomerated, and thus the electric resistance of the electroconductive film 4 does not become sufficiently low. This reason is considered to be because the copper particles 21 which are not sufficiently sintered are present in the conductive film 4.

Next, as shown in FIG. 1(e), the sintering accelerator 5 is attached to the conductive film 4. The sintering accelerator 5 is also adhered to the conductive film 4 by applying the sintering accelerator 5 on the conductive film 4. The sintering accelerator 5 can be attached to the electroconductive film 4 by welding or vapor deposition by irradiation with light.

The sintering accelerator 5 is a compound that removes copper oxide from metallic copper. The sintering accelerator 5 is, for example, a guanamine, a melamine, a ketone, a carbamate, a thioether, a carboxylic acid, or a phosphoric acid. Examples of the sintering accelerator 5 include, but are not limited to, guanamines such as polyglycolic acid, polyvinylpyrrolidone, dimethylacetamide, and dimethylformamide; for example, polyamidamine film, poly a decylamine, and a melamine of a polyamidoximine; a ketone such as acetamidine and γ-butyrolactone; a carboxylic acid such as acetic acid and a low molecular weight unsaturated polycarboxylic acid polymer; Phosphoric acid phosphates. Such a sintering accelerator 5 is considered to remove copper oxide from metallic copper by etching.

The sintering accelerator 5 may be an alcohol, a saccharide, an aldehyde, a hydrazine, an anthracene, a phenol, or an amine. Examples of the sintering accelerator 5 include, but are not limited to, for example, methanol, isopropanol, ethylene glycol, 3-methoxy-3-methylbutanol, diethylene glycol mono-2-ethylhexyl ether, and Alcohols of polyethylene glycol; such as saccharides of L-sorbitol and Kent paper; aldehydes such as furfural; hydrazines such as hydrazine; hydrazines such as hydroquinone; phenols such as hydroxybutylanisole And; amines such as hydroxylamine, triethanolamine, and ifolin. Such a sintering accelerator 5 is removed from the metallic copper by reducing the copper oxide.

These sintering accelerators 5 may be used singly or two or more kinds of sintering accelerators may be appropriately mixed and used.

Next, the conductive film 4 having the adhered sintering accelerator 5 is further photo-sintered. As shown in Fig. 1(f), in this photo sintering, the electroconductive film 4 is sufficiently agglomerated to form a conductive film 6 having a low electric resistance.

So far, the surface oxide film of the copper particles 21 has been considered to be due to light sintering. The light energy is reduced to copper by photoreduction and then removed.

However, according to the test performed by the inventors of the present invention, even if the energy of the light irradiated in the photo sintering is increased, the copper fine particle layer may not be sufficiently agglomerated depending on the copper particulate dispersant. Since the excessive energy of the light irradiated on the copper particle layer may cause damage to the copper particle layer, there is a limit in strength of the light energy irradiated in the light sintering. The inventors of the present invention believe that there may be some cases where the surface oxide film of the copper particles 21 is not sufficiently removed due to the light energy, and thus the light sintering is not sufficiently performed, resulting in insufficient agglomeration of the copper particle layer.

The inventors of the present invention have been able to carry out photo sintering by testing using a compound which removes copper oxide from metallic copper. In the conductive film forming method of the present embodiment, the sintering accelerator 5 is a compound that removes copper oxide from the metallic copper, and the surface oxide film of the copper fine particles 21 is removed, and the surface oxide film is present in the conductive film 4. It is not fully sintered. The irradiation of light to the electroconductive film 4 having the attached sintering accelerator 5 promotes a chemical reaction in which the sintering accelerator 5 removes copper oxide from the copper particles 21. In the photo sintering after the sintering accelerator 5 is attached to the electroconductive film 4, the copper particles 21 from which the surface oxide film has been removed are sintered by the light energy, and thus the electroconductive film 4 is agglomerated to form a low resistance. Conductive film 6.

As described above, according to the conductive film forming method of the present embodiment, in the photo sintering after the sintering accelerator 5 is attached to the conductive film 4, the surface of the copper particles 21 in the conductive film 4 is removed by the sintering accelerator 5. The oxide film further sinters the copper fine particles 21 from which the surface oxide film has been removed, so that the conductive film 6 having low resistance is easily formed.

If the sintering accelerator 5 achieves etching of copper oxide, the surface oxide film of the copper particles 21 is removed by etching.

If the sintering accelerator 5 achieves the reduction of copper oxide, the surface oxide film of the copper particles 21 is removed by reduction.

In the following examples, the conductive film 6 is formed by the conductive film forming method of the present invention, and the electric resistance of the conductive film 6 thus formed is measured.

[Example 1]

Alkaline-free glass was used as the substrate 1. A copper particulate dispersant (manufactured by ISHIHARA CHEMICAL CO., LTD., trade name "CJ-0104") was applied onto the substrate 1 by a spin coating method at a predetermined thickness. The substrate 1 covered with the copper particulate dispersant was dried at 100 ° C for 30 minutes under the atmosphere, and then subjected to photo sintering using a flash irradiation device having a xenon lamp. The light irradiation in the photo sintering is performed at an energy intensity in a range from 0.5 J/cm ² to 30 J/cm ² for 0.1 ms to 10 ms, and under this condition, it can be obtained by a single irradiation to have about 1000 mΩ/□. The sheet of resistive conductive film 4. The conductive film 4 thus obtained has a black surface and is not completely sintered. However, coating the liquid on the film does not cause any copper particles 21 to be dissolved in the liquid. Next, methanol among the alcohols is used as the sintering accelerator 5, the sintering accelerator 5 is coated on the electroconductive film 4, and second photo sintering is performed to produce a test substrate. The light irradiation in the second photo sintering is performed for 0.1 ms to 10 ms with an energy intensity in a range from 0.5 J/cm ² to 30 J/cm ² , and the irradiated light has an energy larger than that of the first light-sintered light. After the second photo sintering, the surface color of the electroconductive film 4 becomes a copper color. The copper color is the color of the agglomerated copper, and the conductive film 6 is formed on the test substrate by the agglomeration action of the conductive film 4 due to the color change of the light sintering. The sheet resistance of the electroconductive film 6 showed a low value of 170 mΩ/□.

[Example 2]

Isopropanol among the alcohols is used as the sintering accelerator 5. A test substrate was produced in the same manner as in Example 1 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 3]

Ethylene glycol among the alcohols is used as the sintering accelerator 5. Except for the above, the test substrate was produced in the same manner as in Example 2. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 440 mΩ/□.

[Example 4]

3-methoxy-3-methylbutanol among the alcohols was used as the sintering accelerator 5. A test substrate was produced in the same manner as in Example 3 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 160 mΩ/□.

[Example 5]

As the sintering accelerator 5, diethylene glycol mono-2-ethylhexyl ether among the alcohols was used. Except for the above, the test substrate was produced in the same manner as in Example 4. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 160 mΩ/□.

[Example 6]

As the sintering accelerator 5, polyethylene glycol (having a molecular weight of 600) among the alcohols was used. A test substrate was produced in the same manner as in Example 5 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 260 mΩ/□.

[Example 7]

Furfural (furan-2-carbaldehyde) among the aldehydes was used as the sintering accelerator 5. Except for the above, the test substrate was produced in the same manner as in Example 6. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 300 mΩ/□.

[Example 8]

As the sintering accelerator 5, dimethylacetamide among guanamines was used. Except for the above, the test substrate was produced in the same manner as in Example 7. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 9]

As the sintering accelerator 5, dimethylformamide among guanamines was used. A test substrate was produced in the same manner as in Example 8 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 10]

Acetylacetone among the ketones was used as the sintering accelerator 5. Except for the above, the test substrate was produced in the same manner as in Example 9. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 350 mΩ/□.

[Example 11]

Γ-butyrolactone among ketones was used as the sintering accelerator 5. Except for the above, the test substrate was produced in the same manner as in Example 10. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 400 mΩ/□.

[Example 12]

Acetic acid among the carboxylic acids is used as the sintering accelerator 5. Except for the above, a test substrate was produced in the same manner as in Example 11. Conductive film 6 formed on the test substrate The surface is copper. The sheet resistance of the electroconductive film 6 showed a low value of 200 mΩ/□.

[Example 13]

A solution containing the sintering accelerator 5 was prepared by using L-sorbitol among the saccharides as the sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L (M). The sintering accelerator 5 is attached to the electroconductive film 4 by coating this solution on the electroconductive film 4, and then the second photo sintering is performed. Except for the above, the test substrate was produced in the same manner as in Example 12. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 400 mΩ/□.

[Example 14]

A solution containing the sintering accelerator 5 is prepared by using hydrazine in the hydrazine as the sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 13 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 180 mΩ/□.

[Example 15]

Hydrogen hydrazine in the hydrazine is used as the sintering accelerator 5, and propylene carbonate is used as the solvent to prepare a solution containing the sintering accelerator 5. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 14 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 260 mΩ/□.

[Example 16]

A solution containing the sintering accelerator 5 was prepared by using hydroxybutyl anisole among phenols as a sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 15 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 17]

A solution containing the sintering accelerator 5 was prepared by using a hydroxylamine among the amines as the sintering accelerator 5 and using propylene carbonate as a solvent. Sintering accelerator 5 The concentration was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 16 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 170 mΩ/□.

[Example 18]

A solution containing the sintering accelerator 5 was prepared by using triethanolamine among the amines as the sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 17, except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 170 mΩ/□.

[Example 19]

A solution containing the sintering accelerator 5 is prepared by using okolinine among the amines as the sintering accelerator 5 and using propylene carbonate as the solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. A test substrate was produced in the same manner as in Example 18 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 200 mΩ/□.

[Example 20]

A solution containing the sintering accelerator 5 was prepared by using polyamine acid in the guanamine as the sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1%. A test substrate was produced in the same manner as in Example 19 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 21]

A solution containing the sintering accelerator 5 was prepared by using polyvinylpyrrolidone (having a molecular weight of 630000) among guanamines as a sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1 mol/L. In addition to the above, the test substrate was produced in the same manner as in Example 20. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 160 mΩ/□.

[Example 22]

Use of a polyamidamine lacquer (N-methyl-2-pyrrolidone solution) among the amides As the sintering accelerator 5, and using propylene carbonate as a solvent, a solution containing the sintering accelerator 5 was prepared. The concentration of the sintering accelerator 5 was adjusted to 1%. A test substrate was produced in the same manner as in Example 21 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 300 mΩ/□.

[Example 23]

A solution containing the sintering accelerator 5 was prepared by using polyamidoquinone imine in the amide series as the sintering accelerator 5 and using propylene carbonate as a solvent. The concentration of the sintering accelerator 5 was adjusted to 1%. A test substrate was produced in the same manner as in Example 22 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 300 mΩ/□.

[Example 24]

A low molecular weight unsaturated carboxylic acid polymer (manufactured by BYK-Chemie Inc., trade name "DISPERBYK (registered trademark) - P-105") as a sintering accelerator 5 and propylene carbonate as a solvent are used. Thus, a solution containing the sintering accelerator 5 is prepared. The concentration of the sintering accelerator 5 was adjusted to 1%. A test substrate was produced in the same manner as in Example 23 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 25]

A phosphate ester (manufactured by BYK-Chemie Inc., trade name "DISPERBYK (registered trademark) - 111") is used as a sintering accelerator 5, and propylene carbonate is used as a solvent to prepare a sintering accelerator. 5 solution. The concentration of the sintering accelerator 5 was adjusted to 1%. In addition to the above, the test substrate was produced in the same manner as in Example 24. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 240 mΩ/□.

[Example 26]

As a sintering accelerator, polyoxyethylene tridecyl ether phosphoric acid ester (manufactured by DAI-ICHI KOGYO SEIYAKU CO., LTD., trade name "PLYSURF (registered trademark) A212C") is used as a sintering accelerator. 5, and using propylene carbonate as a solvent, thereby preparing a sintering-containing A solution of the agent 5. The concentration of the sintering accelerator 5 was adjusted to 1%. In addition to the above, the test substrate was produced in the same manner as in Example 25. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 400 mΩ/□.

[Example 27]

As a sintering promotion, polyoxyethylene lauryl ether phosphoric acid ester (produced by DAI-ICHI KOGYO SEIYAKU CO., LTD., trade name "PLYSURF (registered trademark) A208B") is used as a sintering accelerator. The solution 5 and the propylene carbonate were used as a solvent to prepare a solution containing the sintering accelerator 5. The concentration of the sintering accelerator 5 was adjusted to 1%. In addition to the above, the test substrate was produced in the same manner as in Example 25. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 400 mΩ/□.

[Example 28]

A slide glass is used as the substrate 1. Except for the above, the test substrate was produced in the same manner as in Example 2. That is, isopropanol among the alcohols is used as the sintering accelerator 5. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 29]

Alumina (ceramic) was used as the substrate 1. A test substrate was produced in the same manner as in Example 28 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 280 mΩ/□.

[Example 30]

Aluminum foil was used as the substrate 1. A test substrate was produced in the same manner as in Example 29 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 500 mΩ/□.

[Example 31]

A stainless steel foil was used as the substrate 1. In addition to the above, the test substrate was produced in the same manner as in Example 30. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 500 mΩ/□.

[Example 32]

A germanium wafer is used as the substrate 1. A test substrate was produced in the same manner as in Example 31 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 200 mΩ/□.

[Example 33]

A slide glass is used as the substrate 1. A polyiminamide film (manufactured by Du Pont-Toray Co., Ltd., trade name "Kapton (registered trademark) 200EN)) was used as the sintering accelerator 5. In the second photo sintering, the conductive film 4 is irradiated with a mask having a light having a larger than standard energy through a polyimide film (which is a sintering accelerator 5) to produce a test substrate. That is, the sintering accelerator 5 is attached to the conductive film 4 by irradiating the sintering accelerator 5 with light. A test substrate was produced in the same manner as in Example 1 except the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 500 mΩ/□.

[Example 34]

A germanium wafer is used as the substrate 1. Kent paper among the saccharides is used as the sintering accelerator 5. In the second photo sintering, a Kent paper as a sintering accelerator 5 is placed in the vicinity of the electroconductive film 4, followed by irradiation with light having a larger than standard energy to produce a test substrate. That is, the sintering accelerator 5 is attached to the conductive film 4 by irradiating the sintering accelerator 5 with light. A test substrate was produced in the same manner as in Example 33 except for the above. The surface of the electroconductive film 6 formed on the test substrate was copper colored. The sheet resistance of the electroconductive film 6 showed a low value of 500 mΩ/□.

In the following comparative example, a conductive film is formed by using a compound which does not remove copper oxide from metallic copper instead of the sintering accelerator 5, and then the electric resistance of the thus formed conductive film is measured.

(Comparative example 1)

Instead of the sintering accelerator 5, propylene carbonate was used. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 2)

The sintering accelerator 5 was replaced with n-hexane. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 3)

Xylene (xylene) was used instead of the sintering accelerator 5. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 4)

Instead of the sintering accelerator 5, liquid paraffin is used. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 5)

The sintering accelerator 5 was replaced with diethylene glycol dibutyl ether. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 6)

The sintering accelerator 5 was replaced with diglyme (bis(2-methoxyethyl) ether). A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 7)

Distilled water was used instead of the sintering accelerator 5. A test substrate was produced in the same manner as in Example 1 except the above. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

(Comparative example 8)

A sintering accelerator 5 was replaced with a PET (polyethylene terephthalate) film. A test substrate was produced in the same manner as in Example 33 except for the above. PET is attached to the conductive film 4 by irradiating the PET film with light. The conductive film formed on the test substrate has a black surface. The sheet resistance of the conductive film showed a high value of 1000 mΩ/□.

As described above, the formation of the conductive film 6 having low electrical resistance is achieved using the sintering accelerator 5. When a compound which does not remove copper oxide from metallic copper is used in place of the sintering accelerator 5, the conductive film thus formed exhibits high electrical resistance.

The present invention is not limited to the configuration of the above embodiment, and does not leave the essence of the present invention. In the case of God or scope, various modifications can still be implemented. For example, the surface shape of the substrate 1 is not limited to a plane, and may be a curved surface or a combination of complex planes.

1‧‧‧Substrate

2‧‧‧Liquid film

3‧‧‧ copper particle layer

4‧‧‧Electrical film

5‧‧‧Sintering accelerator

6‧‧‧Electrical film

21‧‧‧ copper particles

Claims (8)

A method of forming a conductive film, wherein a conductive film is formed by photo sintering, the method comprising the steps of: forming a liquid film made of a copper particulate dispersant on a substrate, drying the liquid film to form a copper particle layer, The copper particulate layer is photo-sintered to form a conductive film, a sintering accelerator is attached to the conductive film, and the conductive film having the sintering accelerator attached thereto is further photo-sintered, wherein the sintering accelerator is removed from the metal copper A compound of copper oxide. The method for forming a conductive film according to claim 1, wherein the sintering accelerator is selected from the group consisting of guanamines, sulfides, ketones, carbamates, thioethers, carboxylic acids, and phosphoric acids. Group. The method for forming a conductive film according to claim 2, wherein the sintering accelerator is selected from the group consisting of polylysine, polyvinylpyrrolidone, dimethylacetamide, dimethylformamide, and polyarylene. A group consisting of an amine film, a polyamidamine lacquer, a polyamidoximine, acetamidine acetone, γ-butyrolactone, acetic acid, a low molecular weight unsaturated polycarboxylic acid polymer, and a phosphate ester. The method for forming a conductive film according to the first aspect of the invention, wherein the sintering accelerator is selected from the group consisting of alcohols, saccharides, aldehydes, hydrazines, hydrazines, phenols, and amines. The method for forming a conductive film according to claim 4, wherein the sintering accelerator is selected from the group consisting of methanol, isopropanol, ethylene glycol, 3-methoxy-3-methylbutanol, and diethylene glycol. Mono-2-ethylhexyl ether, polyethylene glycol, L-sorbitol, Kent paper, furfural, hydrazine, hydroquinone, hydroxybutyl anisole, hydroxylamine, triethanolamine, and florin Group. The method for forming a conductive film according to the first aspect of the invention, wherein the sintering accelerator is coated on the conductive film in a step of attaching a sintering accelerator to the conductive film. The method for forming a conductive film according to the first aspect of the invention, wherein the sintering accelerator is attached to the conductive film by irradiation with light in a step of attaching a sintering accelerator to the conductive film. A sintering accelerator for use in a method of forming a conductive film according to any one of claims 1 to 7.